GEOSTATS: ANN: Subsurface Simulation/Characterization Paper available on web
- Please check the link http://pub.uwrl.usu.edu/~ulall/knn-drill/
to view the paper indicated below. it has been submitted to Water Resources
A k-Nearest Neighbor Bootstrap Simulator of Pseudo-Bore Hole Logs for
Upmanu Lall and Alaa Ibrahim Ali
Utah Water Research Lab. and Dept. of Civil and Environmental Eng.,
Utah State University, Logan UT 84322-8200
Subsurface characterization is important for investigations of groundwater
contamination as well as for petroleum extraction potential. Bore hole
logs are a
common source of localized stratigraphic information. Sampling and
interpolation uncertainties complicate the characterization of the
subsurface from the data.
Geostatistical methods are often used to map subsurface attributes from
such data, and to generate conditional simulations that honor observed
strata. The existing
methods often require an a priori discretization of the bore hole data
along each vertical section into strata types, as well as assumptions as to
homogeneity of the underlying random field that generated the discretized
A method for generating likely realizations of subsurface soils by
resampling pseudo-bore hole logs on to a horizontal grid is presented
here. Entire bore hole logs
are resampled on to the grid locations, thus obviating the need for a prior
discretization of the bore hole data. The bootstrapping algorithm used is
motivated by a
nonhomogeneous random field description of the data with the necessary
probability distributions defined implicitly through a nonparametric
probability density estimate for the sampling distribution of the bore hole
logs (real or pseudo) that lie in a neighborhood of a grid point at which
needed. Example applications to a synthetic and to a real data set are
provided. Extensions to incorporate other sources of information, as well
applications of the method, are discussed.
Professor, Civil and Environmental Engineering
Associate Director, Utah Water Research Laboratory
Utah State University
Logan UT 84322-8200
Phone: 801-797-3184 FAX: 801-797-3663
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